INVESTIGATING YOUR STREAM S DRAINAGE BASIN

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Veronica McGee
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IT S OUR WATER INVESTIGATING YOUR STREAM S STREAM ACTIVITY SUMMARY Using maps, students will determine land uses in the drainage basin of their stream and calculate the approximate percentage of

They will also go outside and verify the information gleaned from maps, and begin monitoring at the places they identified.

use maps and direct evidence to calculate the approximate area in the drainage basin covered by impervious surface. identify points in the stream to monitor based on the land-use information.

1 IT S OUR WATER INVESTIGATING YOUR STREAM S STREAM ACTIVITY SUMMARY Using maps, students will determine land uses in the drainage basin of their stream and calculate the approximate percentage of impervious surface in the basin. Based on this information, they will choose places in the stream that should be monitored on an ongoing basis. They will also go outside and verify the information gleaned from maps, and begin monitoring at the places they identified. OBJECTIVES Students will: use maps and direct evidence to determine the ways that land is used in the drainage basin of their stream. use maps and direct evidence to calculate the approximate area in the drainage basin covered by impervious surface. identify points in the stream to monitor based on the land-use information. monitor water quality in the stream. TIME REQUIRED 90 minutes in Classroom 90 minutes in Field MATERIALS Pencils Field notebooks A variety of maps of stream (topo maps, street maps, aerial photographs, etc. See Resources below for information on sources for maps) Graph paper Cameras or video cameras (optional) Stream monitoring test kits and equipment (see Module 3 stream activity) MAKING CONNECTIONS So much of science is about looking for and making connections. Making connections between, for instance, DDT and the decline of birds of prey. Or connections between chlorofluorocarbons and ozone depletion. In this activity, students will be looking for connections between the water quality in their stream and how the land is used in their stream s watershed. Be sure to make the point that the water quality in this stream also affects the water quality of all the water downstream as well. BACKGROUND Having spent time at the stream, students should be somewhat familiar with the ways in which land in the drainage basin is used. Is it mostly residential? Commercial? Agricultural? Is there a lot of construction going on? In this activity, students will take a more precise look at land uses, and consider how these uses affect the stream. It s important to know how land is being used in a stream s drainage basin to begin to understand what kinds of pollutants might be getting in the stream. When rain falls, some evaporates, some soaks into the ground, and some runs downhill until it joins a stream. In a natural wooded drainage basin, a higher percentage of rain soaks into the ground, where it becomes ground water or is taken up by plant roots. In an urban drainage basin, a higher percentage of rain runs to the nearest stream and does so more quickly because it is flowing over impervious surfaces such as rooftops, streets and parking lots. Rain falling on these impervious surfaces usually goes straight into storm sewers, which lead directly to the nearest creek. This is why urban streams 1

2 flood more readily than streams flowing through undeveloped, vegetated areas. The water that runs off in urban areas brings with it whatever it picks up along the way oil and salt from streets and parking lots, fertilizers and pesticides from lawns. This kind of pollution, which is not from any one specific place, is called non-point source pollution. In contrast, point source pollution comes from one identifiable source for example, effluent being discharged from a factory. Your students are probably used to thinking of factories and cities as polluting, but some pretty idyllic-looking landscapes can also cause problems for streams. Run-off from a neighborhood can contain high concentrations of fertilizers, herbicides, and pesticides from lawns. Run-off from farms also contains fertilizers, pesticides and herbicides, as well as animal wastes that contribute to high levels of nitrate and phosphate. And many people don t know that sediment, whether from a recently plowed field or construction site, is a significant pollutant. Dirt may be natural, but there s nothing natural about dumping large amounts of extra sediment in a stream. Sediment hurts aquatic plants by blocking sunlight, and hurts aquatic animals by clogging gills and by covering up stream-bottom habitats. THEACTIVITY PART I: USING MAPS TO IDENTIFY LAND USES 1. Working in small groups, find your stream and its watershed on topographic and street maps and on satellite or aerial photographs. 2. Trace the stream from one of the maps, using a solid line, on a piece of graph paper. Trace the boundaries of its watershed on the paper using a dashed line. Also write or trace the scale from the map you re tracing onto your map. Trace any important landmarks in the basin, such as roads or buildings. Mark which direction is north. This will be your land-use map. In this activity, your students will be looking at one small drainage basin. But that drainage basin is one of many in a larger drainage basin for a large river that flows to the sea. The water (and pollutants) in this stream will join other streams and eventually the larger river, which can become quite polluted if each of the smaller streams is even a little polluted. Most likely there are communities downstream depending on this river for drinking water. Make the point that what is going on in this small drainage basin has larger implications. You can use your field monitoring days (when the class is doing its weekly water quality monitoring) to have the class verify the land uses they found on the maps. If you are pressed for time, have half of the class verify land uses and the other half do water quality monitoring. You may also want to limit the scope of land use verification to the school grounds. PROCEDURE A short video with tips on how to implement this activity is available at. WARMUP Have a class discussion, or ask students to write in their field notebooks, using the following questions as prompts: What are some of the ways that land in the stream s watershed is used? How do these uses affect the stream? Do any of these uses pollute the stream? How? Do any of these uses protect the stream? How? 3. Use the maps to identify land uses in the watershed, and label these (including approximate boundaries) on your land-use map. Be as specific as you can. Land uses might include residential (high density or low density?), agricultural (what type?), commercial (offices, shops, mall?), industry (what type?), recreational (walking trails, playing fields), construction, or undeveloped (vacant lots, forested areas, wildlife preserve?). 4. Brainstorm with your group members how the different land uses might affect the stream, either in positive or negative ways. 2

PART II: CALCULATING IMPERVIOUS SURFACE IN THE 1. Impervious surfaces are areas where rain cannot soak into the ground, such as areas covered with pavement or buildings.

3 PART II: CALCULATING IMPERVIOUS SURFACE IN THE 1. Impervious surfaces are areas where rain cannot soak into the ground, such as areas covered with pavement or buildings. First, make note of which areas on your land-use map are clearly all impervious surface (100%) or clearly no impervious surface (0%). Many areas will be a mix. For those areas, you will have to estimate. For example, in a residential neighborhood, estimate what percentage of the land is covered by houses, streets, sidewalks and driveways. Label each area on your map with the appropriate percentage. 2. Use the scale to figure out the approximate area of one graph paper square. Count the number of squares in each land-use area that has any impervious surface, estimating where you have partial squares. Multiply the area times the percentage of impervious surface for that land-use. Remember to place your decimal properly when doing so. For example, to figure 90% of a number, multiply the number by Based on what you have learned so far, identify any possible sources of water pollution either point or non-point sources. Point sources might include a discharge pipe from an industrial plant or sewage treatment plant. Non-point sources might include run-off from agricultural areas or from a residential neighborhood with fertilized lawns and oily streets or parking lots. 4. Based on what you have learned about land uses and impervious surface in the drainage basin, choose some places in your stream that you and your group members think are especially important to monitor. For example, if the stream passes through areas with high percentages of impervious surface, you might want to monitor in that area. Or, if you re interested to see whether a tributary is bringing in pollutants, consider monitoring just upstream and just downstream from where the tributary joins your stream. PART III: VERIFYING IN THE FIELD AND MONITORING 1. Spend some time in the field verifying the land uses, particularly for any areas where the maps gave incomplete or contradictory information. 2. Monitor water quality in the areas you and your classmates identified as important, using the testing parameters you used in Module 3. WRAP UP AND ACTION In a class discussion, ask the students some of the questions you asked in the Warm Up. At this point, students should be able to answer the questions in more detail. Did this second round of monitoring turn up any new or different information than the first round? How does knowledge of land-use in the drainage basin add to the students understanding of the study stream? Students will need to gather and polish all their information neatly, to be included in the final report. ASSESSMENT Have students: Describe the mix of land use in the stream s drainage basin on a test or quiz. Describe ways the stream might be different if there were different land-uses in its drainage basin. Explain why and how land-use in any stream s drainage basin has an affect on that stream. EXTENSIONS If you have old and new topographic maps of the stream the class is studying, compare land uses and/or amount of development between the two maps. If there is a significant difference, look for physical evidence to document ways that the stream has been affected. For example, a large increase in development (and impervious surface) usually causes increased flooding and increased erosion in a stream. Look at the banks for evidence of erosion are they steep with fresh surfaces? Are tree roots exposed? 3

4 RESOURCES Color Me a Watershed in Project WET, p Bozeman, Montana: The Watercourse and the Council for Environmental Education. Wilbourne, Ferne B A Guide to Streamwalking. Raleigh, NC: Division of Water Resources, North Carolina Department of Environment and Natural Resources. Reports_and_Publications/Stream_Watch/ MAP RESOURCES FREE Topographic/Satellite/Road Maps: mapper.acme.com United States Geological Survey maps: 888-ASK-USGS ( ) Watersheds: Neuse River Watershed Atlas: extension/wqg/neuse/maps.html Aerial photos: Topographic maps: North Carolina Essential Standards for 8TH GRADE SCIENCE GOALS & OBJECTIVES The stream activities in each module are intricately tied. Although this activity may not be correlated to your standards, it is needed for the complete picture of the stream and to achieve the objectives listed below. 8.E.1: Understand the hydrosphere and the impact of humans on the local systems and the effects of the hydrosphere on humans. ph Nitrates and phosphates Turbidity Bio-indicators 8.E.1.4: Conclude that the good health of humans requires: Monitoring of the hydrosphere Water quality standards Maintaining safe water quality Stewardship for EARTH/ENVIRONMENTAL SCIENCE GOALS & OBJECTIVES EEn.2.4: Evaluate how humans use water. Explain various water uses by humans and evaluate for benefits and consequences of use (ex. wells, aquifer depletion, dams and dam removal, agriculture, recreation). Evaluate the effects of population growth on potable water resources. Infer future effects. Explain how pollutants might flow through a watershed and affect inhabitants that share the same watershed. EEn.2.4.2: Evaluate human influences on water quality in North Carolina s river basins, wetlands, and tidal environments. Evaluate issues of ground water and surface water pollution, wetland and estuary degradation, and salt water intrusion. Evaluate water quality of NC streams (chemical, physical properties, biotic index). Analyze non-point source pollution and effects on water quality (sedimentation, stormwater runoff, naturally and human induced occurrences of arsenic in groundwater). Evaluate conservation measures to maximize quality and quantity of available freshwater resources. 8.E.1.3: Predict the safety and potability of water supplies in North Carolina based on physical and biological factors, including: Temperature Dissolved Oxygen 4

5 Student Page Instructions THEACTIVITY PART I: USING MAPS TO IDENTIFY LAND USES 1. Working in small groups, find your stream and its watershed on topographic and street maps and on satellite or aerial photographs. 2. Trace the stream from one of the maps, using a solid line, on a piece of graph paper. Trace the boundaries of its watershed on the paper using a dashed line. Also write or trace the scale from the map you re tracing onto your map. Trace any important landmarks in the basin, such as roads or buildings. Mark which direction is north. This will be your land-use map. 3. Use the maps to identify land uses in the watershed, and label these (including approximate boundaries) on your land-use map. Be as specific as you can. Land uses might include residential (high density or low density?), agricultural (what type?), commercial (offices, shops, mall?), industry (what type?), recreational (walking trails, playing fields), construction, or undeveloped (vacant lots, forested areas, wildlife preserve?). 4. Brainstorm with your group members how the different land uses might affect the stream, either in positive or negative ways. PART II: CALCULATING IMPERVIOUS SURFACE IN THE 1. Impervious surfaces are areas where rain cannot soak into the ground, such as areas covered with pavement or buildings. First, make note of which areas on your land-use map are clearly all impervious surface (100%) or clearly no impervious surface (0%). Many areas will be a mix. For those areas, you will have to estimate. For example, in a residential neighborhood, estimate what percentage of the land is covered by houses, streets, sidewalks and driveways. Label each area on your map with the appropriate percentage. 2. Use the scale to figure out the approximate area of one graph paper square. Count the number of squares in each land-use area that has any impervious surface, estimating where you have partial squares. Multiply the area times the percentage of impervious surface for that land-use. Remember to place your decimal properly when doing so. For example, to figure 90% of a number, multiply the number by Based on what you have learned so far, identify any possible sources of water pollution either point or non-point sources. Point sources might include a discharge pipe from an industrial plant or sewage treatment plant. Non-point sources might include run-off from agricultural areas or from a residential neighborhood with fertilized lawns and oily streets or parking lots. 4. Based on what you have learned about land uses and impervious surface in the drainage basin, choose some places in your stream that you and your group members think are especially important to monitor. For example, if the stream passes through areas with high percentages of impervious surface, you might want to monitor in that area. Or, if you re interested to see whether a tributary is bringing in pollutants, consider monitoring just upstream and just downstream from where the tributary joins your stream. PART III: VERIFYING IN THE FIELD AND MONITORING 1. Spend some time in the field verifying the land uses, particularly for any areas where the maps gave incomplete or contradictory information. 2. Monitor water quality in the areas you and your classmates identified as important, using the testing parameters you used in Module 3.

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